why can't I assign a keyboard shortcut for "Add Layer Mask"

[ninose11]

I've examined the Keyboard Shortcuts section under Application Menus in Photoshop CC 2018, but there seems to be no way to add a keyboard shortcut for Add Layer Mask. I use this feature all the time, and having to always mouse over to the icon is cumbersome. Isn't there a way to assign a shortcut to that command?

I've tried via the Action Menu but that doesn't work either. It's strange because other Layer Menu commands like Add Layer or Delete Layer are easily assignable. As you can see from this menu shot, even though Apply Layer Mask has Shift+Command+M assigned to it, that doesn't work either.

Is there something I'm missing? Or is it impossible to assign a keyboard shortcut to Add Layer Mask in Photoshop CC?

[Jeff Arola]

You want Layer Mask>Reveal All (white mask)

Layer Mask>Hide All is a black layer mask

Apply is for applying an already made layer mask to the layer itself

(merge the layer mask and layer)

[ninose11]

Thank you very much for your help Jeff. If I could just ask you one more question, the only other shortcut I haven't been able to find is the one for adding a Levels Adjustment in the Layers Panel. Am I missing something here as well? Thank you in advance. 

[Jeff Arola]

You want to go to Edit>Keyboard Shortcuts>Application Menus>Layer>New Adjustment Layer>Levels or Panel Menus>Adjustments>Levels.